1. Field of the Invention
The present invention generally relates to a novel switching rectifier circuit that combines the conventional three-phase, 6-stepped PWM boost rectifier/buck inverter, with a low-power switch commutation circuit. The commutation circuit provides zero-voltage turn-on for the switches, and soft turn-off for the diodes. It is only active during a short period of switching cycle, and it processes only a small fraction of the total power (below 5%), most of which is also transferred to the load.
2. Description of the Prior Art
In many applications it is desirable to have a controlled rectifier/inverter that can provide the following features: output voltage regulation, input power factor correction, low harmonic distortion of the currents drawn from the three-phase lines, minimal number of components and minimal components current and voltage stresses, high power density, and high efficiency. Conventionally, for higher power applications, a 3-phase, PWM boost rectifier/buck inverter has been used to meet the above requirements. However, this circuit suffers from severe switching losses and problems with the reverse recovery of the bridge diodes. In order to reduce the size of the reactive components, switching frequency must be increased, which is, however, accompanied with excessive increase of switching losses.